1. Technical Field
The present invention relates to an apparatus for detecting a toner inside a developing device of an image forming apparatus, whereby an operator can know an amount of remaining toner.
2. Background Art
Conventionally, a toner detecting apparatus includes a sensor, which is provided in a casing of a developing device, to detect a toner inside the developing device. An output signal (voltage) from the sensor is compared with a predetermined fixed threshold value and the amount of toner is indicated based on the comparison result.
However, since a toner agitator is provided in the developing device casing and the toner is often agitated by this agitator, the output voltage from the sensor is influenced by the agitation. Therefore, the output voltage from the sensor substantially always fluctuates and a precise amount of toner cannot be grasped. Further, the output value of the sensor drifts with its own temperature so that the comparison result varies, even if the amount of toner does not change. Consequently, an exact amount of toner cannot be detected.